Occurrence and cover of algae along a transect at the island of Helgoland in 2005

A sublittoral transect (P3) in the North of Helgoland that had been investigated ~40 years earlier by Lüning (1970) was traversed again. Scuba dives were carried out between 21.04.2005 and 23.06.2005. At different sampling points (Location ID: P1-P44; start with P1 every new day) along the transect, substrate and topography was recorded and every 5m occurrence and the cover was obtained of the dominant brown algae Fucus serratus, Sargassum muticum, Laminaria digitata, L. hyperborea and Saccharina latissima. The occurrence was measured qualitatively as present/absence (1/0) and the cover was estimated semi-quantitative according to the Kautsky scale as 0 for not present to 100 as 100% cover (Kautsky, 1995). Furthermore, the transect was split into different zones (1-7) depending on the algal vegetation according to the master thesis of C. Gehling (2006). For each sampling point, time, date and coordinates were given as well as the corrected depth in m mean low water spring tide.